75 Years At Langley

Cowlings Cut Drag

One of Langley's first major breakthroughs came in the late 1920s, when work done in a new 20-foot-diameter wind tunnel resulted in a new type of engine covering.

American airplane builders were experimenting with two cooling systems for airplane engines. Air-cooled engines were designed so that much of the surface area of the engines came in contact with air rushing over the cylinders. But the exposure of the engine meant more resistance to the wind, reducing the airplane's efficiency, according to NASA.

The other system used water to cool the engine. But the water and pumps for the cooling system made the plane heavier. The Army was also finding that the jarring impact of landings on aircraft carriers was causing leaks in the cooling system.

Engineers saw that the answer was to place a cowling around the engine that would reduce the plane's drag but also allow the engine to be cooled. Langley engineers developed 10 cowlings that varied in the amount of engine they covered, according to ``Engineer in Charge,'' a history of Langley by James Hansen.

After hundreds of tests in the Propeller Research Tunnel, built in 1927, Langley engineers found a cowling that improved the performance of the plane while adding little weight. The engine cover had a slot to allow cooling air to enter.

In 1929, a stunt flier added the cowling to a Lockheed monoplane, increasing the plane's speed from 157 to 177 mph. The plane set a record on its nonstop flight from Los Angeles to New York, according to Hansen.

``Record impossible without new cowling,'' Lockheed said in a telegram to NACA. ``All credit due NACA for painstaking and accurate research.''